Killer: Animal residue found on ancient stone tools

Brett Smith for redOrbit.com – @ParkstBrett

As we humans began to evolve larger and larger brains, we needed to start eating more and more meat to fuel our expanding brain power. However, we lacked the razor-sharp teeth and claws that our fellow meat-eaters used to kill and extract meat from an animal.

Now, for the first time, researchers have found evidence that hand-axes, scrapers and other stone tools were used to butcher an animal after a kill, according to a new report in the journal PLoS ONE.

In the report, an analysis of 500,000-year-old stone tools found among animal remains revealed animal residues on the tools, which the study team said was direct evidence of their use in processing animal carcasses.

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“There are three parts to this puzzle: the expansion of the human brain, the shift to meat consumption, and the ability to develop sophisticated technology to meet the new biological demands. The invention of stone technology was a major breakthrough in human evolution,” said study author Ran Barkai, an archeologist at Tel Aviv University. “Fracturing rocks in order to butcher and cut animal meat represents a key biological and cultural milestone.”

The elephant in the room

To reach their finding, the study team conducted a use-wear investigation, which looked at the surfaces and edges of the tools to figure out their function. The scientists also used a Fourier Transform InfraRed (FTIR) residue evaluation, which used infrared to recognize signatures of prehistoric organic compounds.

“Archaeologists have until now only been able to suggest scenarios about the use and function of such tools. We don’t have a time machine,” Barkai said. “It makes sense that these tools would be used to break down carcasses, but until evidence was uncovered to prove this, it remained just a theory.”

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Even before the publishing of this study, archeologists were fairly sure that hand-axes and scrapers were used to break down a carcass. These tools are seen at prehistoric locations worldwide. After replication the tools and conducting a butchering experiment, the scientists established that the hand-axe was effective at cutting and breaking down bone, tough connective tissue, and hide. The thinner, more fragile scraper was used to split up fur and animal fat from muscle.

“Prehistoric peoples made use of all parts of the animal,” Barkai said. “In the case of the massive elephant, for example, they would have needed to use both tools to manage such a challenging task. The knowledge of how to make these tools was precious, and must have been passed along from generation to generation, because these tools were reproduced the same way across great territorial expanses and over hundreds of thousands of years.”

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